1. Technical Field
The claimed invention relates generally to telecommunications. More particularly, the claimed invention relates to a system, method and apparatus for interference protection in a telecommunications system.
2. Description of Related Art
Generally, wireless office systems (WOS) and more particularly digital wireless office systems (D-WOS) are well known in the art. Such wireless office systems can either stand-alone or are adjuncts to private-branch exchanges (PBXs). (WOS and D-WOS will be referred to as WOS hereinafter.) A PBX is a private telephone switch serving several extensions for establishing end-to-end connectivity among users, supervising the communication circuit and tearing down a communication path upon terminating or disconnecting a call. The PBX system is generally used as a corporate voice network within one building or several buildings situated on a campus. Communications are generally handled between users within the PBX system or between the PBX system and the public switched telephone network (PSTN) including mobile telephone wireless networks.
The WOS converts a PBX extension into a mobile phone extension such that a user with a mobile telephone can carry on communications with the mobile telephone. Accordingly, the WOS performs communication hand-offs between general-purpose mobile wireless communication networks (the macro-network hereinafter) and the WOS (and vice-versa) while the user moves about into and out of the building or campus that houses the PBX system. The user also can use the mobile telephone over a limited outdoor campus area, for example. However, because the WOS operates on wireless communication principles, there is an inherent tendency for such systems to interfere with the macro-network because the WOS can use the same frequencies, or channels, as ones that are allocated to the macro-network.
Generally, the WOS uses frequencies on the wireless frequency spectrum that are unused. A wireless office scanner is used to select a communication channel from the unused frequencies on the wireless spectrum. The scanner scans for frequencies that are used by the macro-network and deems such frequencies as unusable by the WOS. However, although the scanners are employed in order to prevent interference with the macro-network, in the event that the scanner should fail, the channels that were deemed unusable by the scanner would be put back in service. In other words, related art WOSs rely on the operation of the scanner to continuously provide a useable frequency spectrum to the WOSs. Accordingly, in a WOS deployment there exists the potential for interference by the WOS to the macro-network if the same frequencies are used by the WOS and the macro-network. Therefore, in the event the scanner becomes defective and fails to scan for local frequencies being used by the macro-network, the WOS will reuse any available frequencies. Related art methods, systems and apparatuses provide some protection by manually removing certain channels from use by the WOS. However, the manual process is labor intensive and, with the introduction of automated channel allocation (ACA), the manual process becomes increasingly more difficult and impractical to use.
Therefore, there is a need to provide a method, system and apparatus to mitigate the potential interference to the macro-network in the event of a catastrophic failure of a WOS scanner. Furthermore, there also is a need to provide a method, system and apparatus to communicate between a WOS and a macro-network for gathering information about macro-network channel reuse within a geographic area in proximity of a building or campus utilizing a WOS. Such information would be useful in determining which frequencies are being used by the macro-network and then removing such frequencies from service so as not to be used by the WOS.